The (true ...) fallback in parse-cmd previously accepted any expression
as a command. Now it checks that the parsed expression's head is `call`
or `method-call` — the only valid forms for pseudo-commands (foo() or
foo.bar()). Any other expression (e.g. foo.bar + bar) raises a parse
error instead of silently becoming a no-op.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>